1. Field of the Invention
The invention relates to a microprocessor-assisted sewing machine control equipment comprising a computer unit with a memory for a sewing machine control program; and a power output unit with drivers for power controlling a controlled sewing machine driving motor and at least another electric motor; the sewing machine driving motor being controlled by closed-loop control through a control system in dependence on its rotary position; and the at least one electric motor being controlled in a manner tuned to the position of the sewing machine driving motor.
2. Background Art
A control equipment of the generic type is known from U.S. Pat. No. 4,787,326 A. The basic control equipment structure there used includes a computer unit with a memory in the form of a data carrier in which to deposit a sewing-machine control program. This controls an automatic sewing machine which comprises a work piece holder that is movable in two coordinate directions and a sewing head that is rotary about an axis and serves for producing a seam on a work piece in accordance with a pattern given by the program. Electric motors are provided, producing the motion of the work piece holder and the rotation of the sewing head; they are triggered for power via a power output unit with corresponding drivers in the same way as the sewing machine driving motor.
The sewing machine driving motor is controlled and triggered by a control equipment in dependence on its rotary position. The electric motors, which are equipped with rotary-position transmitters, are triggered in a manner tuned to the position of the driving motor of the sewing machine.
Drawbacks of the known control equipment reside in that it is designed for practical application in a specific case. For an electric motor that is to be triggered irrelevantly of the position of rotation, a simple open-loop control unit is provided, having no rotary-position signal feedback; whereas a corresponding closed-loop control unit inclusive of rotary-position signal feedback is employed for an electric motor that is controlled in dependence on the position of rotation. If a sewing device of a different type is to be triggered, which comprises additional electric motors of deviating configuration, a specifically suited controlling equipment must be created. This implies highly complicated development and manufacturing jobs accompanied with correspondingly high manufacturing cost, because special construction of the respective control equipment is needed, which will as a rule be implemented by small-scale manufacture.
Proceeding from these problems, it is an object of the invention to develop the known sewing machine control equipment such that it is universally employable regardless of the specific configuration of the connected electric motors and the control thereof in dependence on, or independently of, the position of rotation.
This gist of the invention is the controlling system that is allocated to a respective electric motor, creating the necessary all-purpose character. This control system comprises an open-loop control unit for triggering the electric motor regardless of the position of rotation as well as a closed-loop control unit for controlled triggering of the electric motor in dependence on the rotary position and on the basis of a rotary-position signal emitted by a rotary-position detector that is disposed on the electric motor. A selection unit that is allocated to the open-loop and closed-loop control units provides for either the open-loop or the closed-loop control unit, in dependence on the configuration of the connected electric motor, to be coupled for control with this motor. If the electric motor has to be controlled in dependence on the rotary position, the closed-loop control unit is coupled in circuit with the electric motor, whereas, in the case of control regardless of the rotary position, the open-loop control unit is coupled via the selection unit.
Given the above-mentioned basic architecture and a certain number of identical control units for a corresponding number of electric motors, the entire control equipment according to the invention can virtually be suited to the controlling requirements of the electric motors in circuit. Regardless of this, the actual sewing machine driving motor for needle motion is customarily controlled in dependence on the rotary position.